Effects Of Biochar Amendment On Soil Quality, Crop Yield In Northwest China

With a rotation of wheat and corn as the selected crops and cultivation mode, this study took field and pot experiment to explore the effects of different ways of returning biomass(adding biochar, returning straw, and adding biochar and returning straw together) on Loess Soil property, nutrient status and crop yield under normal water condition, and to research the influence of biochar on the property of Loess Soil, Loessal Soil and Sandy Soil in the Northwest region, nutrient status and crop yield under drought condition. The results showed that:1. Effects of different ways to return biomass on soil and cropsUsing winter wheat and summer maize as the research object, with straw and its biological biochar as the research material, this study explored the effects of different ways of returning biomass on Loess Soil chemical property, soil nutrient status, crop yield, biomass and crop nutrient content under normal water condition by field experiment. The results showed that: in the first period(10/2013- 6/2014), all treatment obviously improved the physical and chemical property of soil, in which the effect of adding biochar at 3 t ha-1 and returning straw at 10 t ha-1 was most obvious; all treatment blocked the nutrient uptake of wheat, which was especially obvious in returning straw at 10 t ha-1 and using both of them at the same time; all the treatment did not significantly affect the wheat yield. In the second period(6/2014- 10/2014), all treatment obviously improved the physical and chemical property of soil, in which the effect of adding biochar was most obvious, and the effect increased with the increase of adding amount; adding biochar obviously improved soil nutrient levels, but the effect decreased with the increase of adding amount; only adding biochar at 15 t ha-1 obviously promoted the crop nutrient absorption, and the other processing blocked crop nutrient uptake, but there was no significant impact of all processing on maize yield. In the third period(10/2014- 6/2015), adding biochar only, or adding biochar and straw together obviously improved the physical and chemical property of soil and promoted crop nutrient absorption. Adding biochar and straw at 10 t ha-1 significantly increased wheat yield, the production effect was obvious with the increase of biochar amount.2. Effects of returning biomass on Loess Soil property and crop growth under drought stressWith the common Loess Soil in Guanzhong region of Shaanxi Province and widely planted rotation crops of wheat and corn as research object, this study explored the effect of returning biomass on the chemical property of drought Loess Soil, nutrient uptake and yield by pot experiment. The results showed that: in the first period(10/2013- 6/2014), the drought significantly led to the deterioration of chemical property of Loess Soil, but it improved soil nutrient condition in a certain extent; meanwhile, although it significantly hindered nutrient absorption, yet it had no significant effect on thousand seed weight of wheat grain; adding biochar at 1.5-3 t ha-1and returning straw at 20 t ha-1 obviously improved the chemical property of drought Loess Soil; all the treatment obviously improved nutrient status of drought Loess Soil, in which the effect of adding biochar at 1.5 t ha-1was most obvious; returning biomass had no obvious effect on crop nutrient absorption, which even got negative effects; all process of adding biochar and straw at 10-20 t ha-1 significantly lowered thousand seed weight of wheat grain. In the second period(6/2014- 10/2014), the drought improved soil nutrient status of Loess Soil in a certain extent, but the other chemical property deteriorated significantly at the same time, and it significantly hindered the corn nutrient absorption; adding biochar at any level significantly improved the chemical property of drought soil, and the effect increased with the increase of adding amount; the treatment of adding biochar and straw at 5 t ha-1 further improved nutrient status of drought Loess Soil, in which the effect was obvious when adding biochar at 60 t ha-1; only adding biochar at 15-30 t ha-1 and returning straw at 10 t ha-1 obviously promoted the crop nutrient uptake, and the effect of the latter was most obvious; adding biochar at 60 t ha-1 and returning straw at 5 t ha-1 obstructed crop nutrient absorption; all level of returning biomass had no significant influence on thousand seed weight of corn grain. In the third period(10/2014- 6/2015), the drought improved chemical property and nutrient status of Loess Soil in a certain extent, and it overall promoted crop nutrient uptake, but significantly decreased thousand seed weight of wheat grain; only adding biochar at 30-60 t ha-1 and returning straw at 20 t ha-1 further improved the chemical property of drought Loess Soil, while other treatment had an adverse effect; only adding biochar at 60 t ha-1 obviously improved nutrient status of drought Loess Soil, while returning straw at 20 t ha-1 had more obvious adverse effect; only returning straw at 5-10 t ha-1 further improved crop nutrient absorption, while the effect of other treatment was not obvious; but returning straw at 5-10 t ha-1 led to further reduction of thousand seed weight of wheat grain.3. Effects of biochar on three types of soil property and crop growth under drought stressWith the common Loess Soil, Loessal Soil and Sandy Soil in the Northwest region and widely planted rotation crops of wheat and corn as research object, this study explored the effect of adding biochar on the chemical property of three types of Soil, nutrient uptake and yield by pot experiment. The results showed that: in the first period(10/2013- 6/2014) the drought led to the deterioration of chemical property of Loess Soil, but it improved soil nutrient status in a certain extent; it significantly hindered plant nutrient absorption at the same time, but it had no significant effect on the thousand seed weight of wheat grain; adding biochar at 1.5-3 t ha-1 obviously improved the chemical property of drought soil; all the treatment further improved soil nutrient status, in which the effect of adding biochar at 1.5 t ha-1 was obvious, while adding biochar at 6 t ha-1 significantly hindered the crop nutrient absorption, and all levels of adding biochar significantly reduced the thousand seed weight of wheat grain. In the second period(6/2014- 10/2014), the drought led to the significant deterioration of chemical property of Loess Soil, but it improved soil nutrient status and promoted crop nutrient absorption in a certain extent; adding biochar at all level significantly improved the chemical property of drought soil, in which the effect of adding biochar at 30 t ha-1 was obvious; adding biochar at all level further improved the fertility condition of drought soil and crop nutrient absorption, in which adding biochar at 60 t ha-1 got obvious effect of improving soil nutrient status, and adding biochar at 15 t ha-1 got the most obvious effect of promoting crop nutrient absorption. In the third period(10/2014- 6/2015), the drought improved the chemical property and nutrient status of Loess Soil in a certain extent, and overall promoted crop nutrient uptake, but it significantly decreased the thousand seed weight of wheat grain; only adding biochar at 30-60 t ha-1 further improved the chemical property of drought soil, while adding at 15 t ha-1 had an adverse effect; only adding biochar at 60 t ha-1 obviously improved nutrient status of drought soil, while adding at 15-30 t ha-1 had more obvious adverse effect; and adding biochar at 60 t ha-1 obviously inhibited the crop nutrient absorption.On average, in the second period(6/2014- 10/2014), the drought stress obviously improved the chemical property of Sandy Soil, it had little effect on the soil nutrient status, and it significantly hindered the crop nutrient absorption, but improved thousand seed weight of corn grain. Adding biochar at all levels further obviously improved the chemical property of drought soil, in which the effect of adding biochar at 30 t ha-1 was obvious. Adding biochar at 30-60 t ha-1 further improved the nutrient status of drought soil, and the effect of adding biochar at 60 t hm-2was most obvious. Adding biochar at all levels obviously promoted the crop nutrient uptake, in which the effect of adding biochar at 30-60 t ha-1 was most obvious. But adding biochar significantly reduced the thousand seed weight of grain. In the third period(10/2014- 6/2015), the drought improved the chemical property and nutrients of Sandy Soil in a certain extent, but overall it suppressed the crop nutrient uptake, and significantly decreased the thousand seed weight of wheat grain. Adding biochar at all levels significantly improved the chemical property and nutrient status of drought Sandy Soil, and promoted nutrient absorption, and the effects were obvious with the increase of adding amount. Adding biochar in drought Sandy Soil had no function on the reduction of the thousand seed weight of wheat grain which was caused by drought Sandy Soil.On average, in the second period(6/2014- 10/2014), the drought had little effect on the chemical property of Loessal Soil and nutrient absorption, yet it caused significant deterioration of the soil nutrient status, but it improved thousand seed weight of corn grain. Adding biochar at all levels significantly worsen chemical property of Loessal Soil and hindered the crop nutrient absorption, in which adding biochar at 30 t ha-1 had the most obvious degradation effect on soil chemical property, adding biochar at 15 t ha-1 had the most obvious hindering effect on nutrient absorption, adding biochar at 30-60 t ha-1 obviously improved the nutrient status in drought soil, and adding biochar at 30 t ha-1 also further improved thousand seed weight of corn grain in Loessal Soil. In the third period(10/2014 – 6/2015), the drought caused the deterioration of chemical property and nutrient status of Loessal Soil, but it had no obvious effect on the nutrient absorption, and it significantly increased the thousand seed weight of wheat grain. Adding biochar at all levels significantly improved the chemical property and nutrient status of drought Sandy Soil, and its effect was obvious with the increase of adding amount. Adding biochar at 15 t ha-1 hindered the nutrient absorption, but adding biochar at 30-60 t ha-1 significantly promoted the crop nutrient uptake, and the effect was obvious with the increase of adding amount. But the adding of biochar significantly reduced the thousand seed weight of wheat grain, of which the under drop is most obvious when adding biochar at 30 t ha-1.